scholarly journals The Poly-γ-d-Glutamic Acid Capsule of Bacillus anthracis Enhances Lethal Toxin Activity

2011 ◽  
Vol 79 (9) ◽  
pp. 3846-3854 ◽  
Author(s):  
Jeyoun Jang ◽  
Minhui Cho ◽  
Jeong-Hoon Chun ◽  
Min-Hee Cho ◽  
Jungchan Park ◽  
...  
Keyword(s):  
Glutamic Acid ◽  
Bacillus Anthracis ◽  
Protective Antigen ◽  
Immune Surveillance ◽  
Lethal Toxin ◽  
Mitogen Activated Protein Kinase ◽  
Content Type ◽  
Mitogen Activated Protein ◽  
Anthrax Infection ◽  
Processed Form

ABSTRACTThe poly-γ-d-glutamic acid (PGA) capsule is one of the major virulence factors ofBacillus anthracis, which causes a highly lethal infectious disease. The PGA capsule disguisesB. anthracisfrom immune surveillance and allows its unimpeded growth in the host. The PGA capsule recently was reported to be associated with lethal toxin (LT) in the blood of experimentally infected animals (M. H. Cho, et al., Infect. Immun. 78:387-392, 2010). The effect of PGA, either alone or in combination with LT, on macrophages, which play an important role in the progression of anthrax disease, has not been thoroughly investigated. In this study, we investigated the effect of PGA on LT cytotoxicity using the mouse macrophage cell line J774A.1. PGA produced a concentration-dependent enhancement of the cytotoxicity of LT on J774A.1 cells through an enhancement in the binding and accumulation of protective antigen to its receptors. The increase of LT activity was confirmed using Western blot analysis, which showed that the combination of PGA and LT produced a greater degree of degradation of mitogen-activated protein kinase kinases and an increased level of the activation of the proform of caspase-1 to its processed form compared to the effects of LT alone. In addition, mice that received a tail vein injection of both PGA and LT had a significantly increased rate of death compared to that of mice injected with LT alone. PGA had no effect when added to cultures or administered to mice in the absence of LT. These results emphasize the importance of PGA in the pathogenesis of anthrax infection.

scholarly journals Anthrax Lethal Toxin Impairs CD1d-Mediated Antigen Presentation by Targeting the Extracellular Signal-Related Kinase 1/2 Mitogen-Activated Protein Kinase Pathway

2010 ◽  
Vol 78 (5) ◽  
pp. 1859-1863 ◽  
Author(s):  
Masood A. Khan ◽  
Richard M. Gallo ◽  
Randy R. Brutkiewicz
Keyword(s):  
Immune System ◽  
Protein Kinase ◽  
Bacillus Anthracis ◽  
Antigen Presentation ◽  
Specific Inhibitor ◽  
Lethal Toxin ◽  
Mitogen Activated Protein Kinase ◽  
Dependent Manner ◽  
Extracellular Signal ◽  
Mitogen Activated Protein

ABSTRACT Lethal toxin (LT) is a critical virulence factor of Bacillus anthracis and an important means by which this bacterium evades the host's immune system. In this study, we demonstrate that CD1d-expressing cells treated with LT have reduced CD1d-mediated antigen presentation. We earlier showed an important role for the mitogen-activated protein kinase extracellular signal-regulated kinase 1/2 (ERK1/2) in the regulation of CD1d-mediated antigen presentation, and we report here that LT impairs antigen presentation by CD1d in an ERK1/2-dependent manner. Similarly, LT and the ERK1/2 pathway-specific inhibitor U0126 caused a decrease in major histocompatibility complex (MHC) class II-mediated antigen presentation. Confocal microscopy analyses revealed altered intracellular distribution of CD1d and LAMP-1 in LT-treated cells, similar to the case for ERK1/2-inhibited cells. These results suggest that Bacillus anthracis has the ability to evade the host's innate immune system by reducing CD1d-mediated antigen presentation through targeting the ERK1/2 pathway.

scholarly journals GeneChip Analyses of Global Transcriptional Responses of Murine Macrophages to the Lethal Toxin of Bacillus anthracis

2005 ◽  
Vol 73 (3) ◽  
pp. 1879-1885 ◽  
Author(s):  
Jason E. Comer ◽  
Cristi L. Galindo ◽  
Ashok K. Chopra ◽  
Johnny W. Peterson
Keyword(s):  
Bacillus Anthracis ◽  
Intracellular Signaling ◽  
Lethal Toxin ◽  
Mitogen Activated Protein Kinase ◽  
Transcriptional Responses ◽  
Murine Macrophages ◽  
Mitogen Activated Protein ◽  
Cell Gene Expression ◽  
Cell Gene ◽  
Protein Kinase Kinase

ABSTRACT We performed GeneChip analyses on RNA from Bacillus anthracis lethal toxin (LeTx)-treated RAW 264.7 murine macrophages to investigate global effects of anthrax toxin on host cell gene expression. Stringent analysis of data revealed that the expression of several mitogen-activated protein kinase kinase-regulatory genes was affected within 1.5 h post-exposure to LeTx. By 3.0 h, the expression of 103 genes was altered, including those involved in intracellular signaling, energy production, and protein metabolism.

scholarly journals Anthrax lethal factor-cleavage products of MAPK (mitogen-activated protein kinase) kinases exhibit reduced binding to their cognate MAPKs

2004 ◽  
Vol 378 (2) ◽  
pp. 569-577 ◽  
Author(s):  
A. Jane BARDWELL ◽  
Mahsa ABDOLLAHI ◽  
Lee BARDWELL
Keyword(s):  
Protein Kinase ◽  
Protective Antigen ◽  
Signal Transmission ◽  
Lethal Factor ◽  
Lethal Toxin ◽  
Mitogen Activated Protein Kinase ◽  
Cell Surface Receptor ◽  
Common Mechanism ◽  
Anthrax Lethal Toxin ◽  
Mitogen Activated Protein

Anthrax lethal toxin is the major cause of death in systemic anthrax. Lethal toxin consists of two proteins: protective antigen and LF (lethal factor). Protective antigen binds to a cell-surface receptor and transports LF into the cytosol. LF is a metalloprotease that targets MKKs [MAPK (mitogen-activated protein kinase) kinases]/MEKs [MAPK/ERK (extracellular-signal-regulated kinase) kinases], cleaving them to remove a small N-terminal stretch but leaving the bulk of the protein, including the protein kinase domain, intact. LF-mediated cleavage of MEK1 and MKK6 has been shown to inhibit signalling through their cognate MAPK pathways. However, the precise mechanism by which this proteolytic cleavage inhibits signal transmission has been unclear. Here we show that the C-terminal LF-cleavage products of MEK1, MEK2, MKK3, MKK4, MKK6 and MKK7 are impaired in their ability to bind to their MAPK substrates, suggesting a common mechanism for the LF-induced inhibition of signalling.

scholarly journals Expression of either Lethal Toxin or Edema Toxin by Bacillus anthracis Is Sufficient for Virulence in a Rabbit Model of Inhalational Anthrax

2012 ◽  
Vol 80 (7) ◽  
pp. 2414-2425 ◽  
Author(s):  
Julie A. Lovchik ◽  
Melissa Drysdale ◽  
Theresa M. Koehler ◽  
Julie A. Hutt ◽  
C. Rick Lyons
Keyword(s):  
Bacillus Anthracis ◽  
Protective Antigen ◽  
Lethal Factor ◽  
Rabbit Model ◽  
Lethal Toxin ◽  
Content Type ◽  
Edema Factor ◽  
Systemic Dissemination ◽  
Edema Toxin ◽  
Ames Strain

ABSTRACTThe development of therapeutics against biothreats requires that we understand the pathogenesis of the disease in relevant animal models. The rabbit model of inhalational anthrax is an important tool in the assessment of potential therapeutics againstBacillus anthracis. We investigated the roles ofB. anthraciscapsule and toxins in the pathogenesis of inhalational anthrax in rabbits by comparing infection with the Ames strain versus isogenic mutants with deletions of the genes for the capsule operon (capBCADE), lethal factor (lef), edema factor (cya), or protective antigen (pagA). The absence of capsule or protective antigen (PA) resulted in complete avirulence, while the presence of either edema toxin or lethal toxin plus capsule resulted in lethality. The absence of toxin did not influence the ability ofB. anthracisto traffic to draining lymph nodes, but systemic dissemination required the presence of at least one of the toxins. Histopathology studies demonstrated minimal differences among lethal wild-type and single toxin mutant strains. When rabbits were coinfected with the Ames strain and the PA− mutant strain, the toxin produced by the Ames strain was not able to promote dissemination of the PA− mutant, suggesting that toxigenic action occurs in close proximity to secreting bacteria. Taken together, these findings suggest that a major role for toxins in the pathogenesis of anthrax is to enable the organism to overcome innate host effector mechanisms locally and that much of the damage during the later stages of infection is due to the interactions of the host with the massive bacterial burden.

scholarly journals Symmetry Requirements for Effective Blocking of Pore-Forming Toxins: Comparative Study with α-, β-, and γ-Cyclodextrin Derivatives

2011 ◽  
Vol 55 (7) ◽  
pp. 3594-3597 ◽  
Author(s):  
Konstantina Yannakopoulou ◽  
Laszlo Jicsinszky ◽  
Crysie Aggelidou ◽  
Nikolaos Mourtzis ◽  
Tanisha M. Robinson ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Comparative Study ◽  
Bacillus Anthracis ◽  
Protective Antigen ◽  
Lethal Toxin ◽  
Anthrax Toxin ◽  
Cyclodextrin Derivatives ◽  
Content Type

ABSTRACTWe compared the abilities of structurally related cationic cyclodextrins to inhibitBacillus anthracislethal toxin andStaphylococcus aureusα-hemolysin. We found that both β- and γ-cyclodextrin derivatives effectively inhibited anthrax toxin action by blocking the transmembrane oligomeric pores formed by the protective antigen (PA) subunit of the toxin, whereas α-cyclodextrins were ineffective. In contrast, α-hemolysin was selectively blocked only by β-cyclodextrin derivatives, demonstrating that both symmetry and size of the inhibitor and the pore are important.

scholarly journals Metalloproteinase Inhibitors, Nonantimicrobial Chemically Modified Tetracyclines, and Ilomastat Block Bacillus anthracis Lethal Factor Activity in Viable Cells

2005 ◽  
Vol 73 (11) ◽  
pp. 7548-7557 ◽  
Author(s):  
Salih S. Kocer ◽  
Stephen G. Walker ◽  
Brad Zerler ◽  
Lorne M. Golub ◽  
Sanford R. Simon
Keyword(s):  
Bacillus Anthracis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Lethal Factor ◽  
Sodium Dodecyl ◽  
Viable Cell ◽  
Lethal Toxin ◽  
Mitogen Activated Protein Kinase ◽  
Metalloproteinase Inhibitors ◽  
Mitogen Activated Protein ◽  
Chemically Modified Tetracyclines

ABSTRACT Lethal toxin, produced by the bacterium Bacillus anthracis, is a major contributor to morbidity and mortality in animals and humans who have contracted anthrax. One component of this toxin, lethal factor (LF), proteolytically inactivates members of the mitogen-activated protein kinase kinase (MAPKK or MEK) family. In this study we show that CMT-300, CMT-308, and Ilomastat, agents initially characterized as matrix metalloproteinase inhibitors which are in early stages of development as pharmaceuticals, effectively inhibit the zinc metalloproteinase activity of LF. All three inhibitors, CMT-300, CMT-308, and Ilomastat, inhibit LF-mediated cleavage of a synthetic peptide substrate based on the N-terminal domain of MEKs. Inhibition of LF-mediated MEK proteolysis by all three agents was also achieved using lysates of the human monocytoid line MonoMac 6 as sources of MAPKKs and visualization of the extent of cleavage after separation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by detection by Western blotting. Finally, we have demonstrated inhibition of intracellular MEKs in viable human monocytes and MonoMac 6 cells by these agents after incubation of the cells with a reconstituted preparation of recombinant lethal toxin. All three agents are effective inhibitors when incubated with LF prior to exposure to cells, while the CMTs, but not Ilomastat, are also effective when added after LF has already entered the viable cell targets. These results offer promise for strategies to combat effects of the lethal toxin of B. anthracis.

scholarly journals Bacillus anthracis Spores Stimulate Cytokine and Chemokine Innate Immune Responses in Human Alveolar Macrophages through Multiple Mitogen-Activated Protein Kinase Pathways

2006 ◽  
Vol 74 (8) ◽  
pp. 4430-4438 ◽  
Author(s):  
Kaushik Chakrabarty ◽  
Wenxin Wu ◽  
J. Leland Booth ◽  
Elizabeth S. Duggan ◽  
K. Mark Coggeshall ◽  
...  
Keyword(s):  
Immune System ◽  
Bacillus Anthracis ◽  
Alveolar Macrophages ◽  
Innate Immune System ◽  
Innate Immune ◽  
Mitogen Activated Protein Kinase ◽  
Tnf Α ◽  
Human Alveolar Macrophages ◽  
Mitogen Activated Protein ◽  
Multiple Signaling

ABSTRACT Contact with the human alveolar macrophage plays a key role in the innate immune response to Bacillus anthracis spores. Because there is a significant delay between the initial contact of the spore with the host and clinical evidence of disease, there appears to be temporary containment of the pathogen by the innate immune system. Therefore, the early macrophage response to Bacillus anthracis exposure is important in understanding the pathogenesis of this disease. In this paper, we studied the initial events after exposure to spores, beginning with the rapid internalization of spores by the macrophages. Spore exposure rapidly activated the mitogen-activated protein kinase signaling pathways extracellular signal-regulated kinase, c-Jun-NH2-terminal kinase, and p38. This was followed by the transcriptional activation of cytokine and primarily monocyte chemokine genes as determined by RNase protection assays. Transcriptional induction is reflected at the translational level, as interleukin-1α (IL-1α), IL-1β, IL-6, and tumor necrosis factor alpha (TNF-α) cytokine protein levels were markedly elevated as determined by enzyme-linked immunosorbent assay. Induction of IL-6 and TNF-α, and, to a lesser extent, IL-1α and IL-1β, was partially inhibited by the blockade of individual mitogen-activated protein kinases, while the complete inhibition of cytokine induction was achieved when multiple signaling pathway inhibitors were used. Taken together, these data clearly show activation of the innate immune system in human alveolar macrophages by Bacillus anthracis spores. The data also show that multiple signaling pathways are involved in this cytokine response. This report is the first comprehensive examination of this process in primary human alveolar macrophages.

Effect of delayed anthrax vaccine dose on Bacillus anthracis protective antigen IgG response and lethal toxin neutralization activity

Vaccine ◽  
2013 ◽  
Vol 31 (44) ◽  
pp. 5009-5014 ◽  
Author(s):  
Phillip R. Pittman ◽  
Diana Fisher ◽  
Xiaofei Quinn ◽  
Trevor Schmader ◽  
Julio G. Barrera-Oro
Keyword(s):  
Bacillus Anthracis ◽  
Protective Antigen ◽  
Vaccine Dose ◽  
Lethal Toxin ◽  
Neutralization Activity ◽  
Anthrax Vaccine

scholarly journals Phosphothreonine Lyase Promotes p65 Degradation in a Mitogen-Activated Protein Kinase/Mitogen- and Stress-Activated Protein Kinase 1-Dependent Manner

2018 ◽  
Vol 87 (1) ◽  
Author(s):  
Mingyu Hou ◽  
Wenhui Wang ◽  
Feizi Hu ◽  
Yuanxing Zhang ◽  
Dahai Yang ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Pathogenic Bacteria ◽  
Critical Role ◽  
Nuclear Factor Κb ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Dependent Manner ◽  
Content Type ◽  
Catalytic Active Site ◽  
Mitogen Activated Protein

ABSTRACT Bacterial phosphothreonine lyases have been identified to be type III secretion system (T3SS) effectors that irreversibly dephosphorylate host mitogen-activated protein kinase (MAPK) signaling to promote infection. However, the effects of phosphothreonine lyase on nuclear factor κB (NF-κB) signaling remain largely unknown. In this study, we detected significant phosphothreonine lyase-dependent p65 degradation during Edwardsiella piscicida infection in macrophages, and this degradative effect was blocked by the protease inhibitor MG132. Further analysis revealed that phosphothreonine lyase promotes the dephosphorylation and ubiquitination of p65 by inhibiting the phosphorylation of mitogen- and stress-activated protein kinase-1 (MSK1) and by inhibiting the phosphorylation of extracellular signal-related kinase 1/2 (ERK1/2), p38α, and c-Jun N-terminal kinase (JNK). Moreover, we revealed that the catalytic active site of phosphothreonine lyase plays a critical role in regulating the MAPK-MSK1-p65 signaling axis. Collectively, the mechanism described here expands our understanding of the pathogenic effector in not only regulating MAPK signaling but also regulating p65. These findings uncover a new mechanism by which pathogenic bacteria overcome host innate immunity to promote pathogenesis.

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